Mama celebrates her 50th birthday on May 3, 2007, with fruit and vegetables at the Burgers Zoo in Arnhem, Holland. AFP/Getty Images hide caption
chimpanzee chimpanzee
Monkeys' vocal equipment can produce the sounds of human speech, research shows, but they lack the connections between the auditory and motor parts of the brain that humans rely on to imitate words. Brian Jefferey Beggerly/Flickr hide caption
Drone-smashing chimpanzees play at the Burger's Zoo in Arnhem, Netherlands. Courtesy of Burger's Zoo hide caption
Mineral supplements, ape-style: A female chimp called Kana eats clay in the Budongo Forest of Uganda. A.Schel/Budongo Conservation Field Station/Animal Ecology, Utrecht University, The Netherlands hide caption
Should chimps have the same legal rights as these lawyers? Steven Wise, president of the Nonhuman Rights Foundation, who is representing research chimps Hercules and Leo, says yes. Assistant Attorney General Christopher Coulston disagrees. They both made their arguments Wednesday in Manhattan State Supreme Court in New York. Richard Drew/AP hide caption
Star enjoys a moment in the sun at the Chimp Haven sanctuary in Keithville, La. Brandon Wade/AP Images for The Humane Society of the United States and Chimp Haven hide caption
An example of a human precision grip — grasping a first metacarpal from the thumb of a specimen of Australopithecus africanus that's thought to be 2 to 3 million years old. T.L. Kivell & M. Skinner hide caption
Chimpanzees play at Chimp Haven, a retirement home for former research animals, in Keithville, La. Gerald Herbert/AP hide caption
Bonobos at the Lola ya Bonobo sanctuary in the Democratic Republic of Congo. Courtesy of Vanessa Woods hide caption
Don't underestimate the crow. Arif Ali/AFP/Getty Images hide caption